Abstract: A method of providing an image Completely Automatic Public Turing test to tell Computers and Humans Apart (CAPTCHA), and a server thereof. The method includes: outputting an image CAPTCHA including a plurality of images including a determination object image; receiving an image selection from the image CAPTCHA; determining whether a test of the image CAPTCHA is passed, based on the received image selection; and determining what the determination object image means. The images include a first group of images used to determine whether an accessing party passes the image CAPTCHA test and a second group of images unused to determine whether the accessing party passes the image CAPTCHA test. The second group includes the determination object image. The determining of the pass of the image CAPTCHA test is performed by selecting an image representing a correct or incorrect answer from the first group.

Abstract: A method of providing an image Completely Automatic Public Turing test to tell Computers and Humans Apart (CAPTCHA), and a server thereof. The method includes: outputting an image CAPTCHA including a plurality of images including a determination object image; receiving an image selection from the image CAPTCHA; determining whether a test of the image CAPTCHA is passed, based on the received image selection; and determining what the determination object image means. The images include a first group of images used to determine whether an accessing party passes the image CAPTCHA test and a second group of images unused to determine whether the accessing party passes the image CAPTCHA test. The second group includes the determination object image. The determining of the pass of the image CAPTCHA test is performed by selecting an image representing a correct or incorrect answer from the first group.

Abstract: Disclosed is a method for detecting a detoured connection via an anonymous network using changes in round trip times. In the method for detecting a detoured connection, a server receives a plurality of sequential requests constituting one service request; responds to the received plurality of requests; measures round trip times (RTTs) according to the requests and responses, respectively; and distinguishes whether there is a detoured connection to the service request on the basis of a difference between the measured round trip times.

Abstract: The present invention relates to a method and system for storing information using TCP communication, and the method includes a communication connection request operation of transmitting, by a client, to a server a first TCP packet containing a header with a SYN field set to be active and an SEQ field in which a random number generated by the client is included, to request a TCP communication connection with the server, an encryption operation of encrypting, by the server, at least one piece of information to be stored in the first TCP packet, a communication connection confirmation operation of transmitting, by the server, to the client a second TCP packet containing a header with a SYN field set to be active, a SEQ field in which the encrypted information is stored, and an ACK field in which a value obtained by adding 1 to the random number included in the SEQ field of the first TCP packet is stored, a response operation of transmitting, by the client, to the server a third TCP packet containing a header wi